WASHINGTON — The disclosure of National Security Agency secrets by 29-year-old computer systems technician Edward Snowden is drawing new scrutiny of security processes and U.S. intelligence agencies’ reliance on contractors such as Snowden’s employer, Booz Allen Hamilton Holding.

Snowden, who took responsibility for releasing classified documents in a video interview posted online by the British-based Guardian newspaper, shouldn’t have had access to so much classified information and his overreach should have set off internal alarms, Michael Hayden, a former director of the NSA and Central Intelligence Agency, said in an interview.

“Fundamentally, this is not a contractor problem,” Hayden said. “It’s a broader cultural problem; it’s a vetting problem; and it’s how does somebody so junior” get access to so much compartmented intelligence, he said.

More than 1.4 million people hold Top Secret clearances, the highest level, and many of them also have access to a variety of what’s called Sensitive Compartmented Information. To obtain access to TS/SCI information, government officials and contractors must pass the same extensive review process to assure that they can be trusted with the nation’s most sensitive intelligence.

At least 483,000 of them are contractors such as Snowden, who worked at the NSA for the past four years for Booz Allen and other contractors after a stint at the CIA, according to reports by the Guardian and The Washington Post. He obtained his Top Secret clearance for his CIA job.

Sen. Richard Burr, R-N.C., who serves on the Senate intelligence committee, said his biggest question is how Snowden was able to access so much information from a post with Booz Allen he held only briefly.

“How could a guy who was at Booz Allen for three months have top secret compartmented clearance?” Burr said to reporters on Capitol Hill Monday. “There are a lot of questions about whether these were in his purview or part of an effort on his part to accumulate as much as he could to release it.”

Sen. Susan Collins R-Maine, another member of the intelligence committee, said that “the idea that a 29-year- old individual with so little experience” had access to the material is “absolutely shocking.”

The combination of a top secret clearance, access to compartmented information and computer skills is a hot ticket for employment and advancement in today’s intelligence community. The expansion of intelligence activities after the 2001 terrorist attacks on New York City and the Pentagon has coincided with a tsunami of electronic information as mobile phones and the Internet provide new opportunities for technological tradecraft.

The agency collected almost 3 billion pieces of intelligence from U.S. computer networks over 30 days that ended in March, according to a document from Snowden that is said to reflect information from an NSA data-mining tool, Boundless Informant.

“NSA’s systems environment is a haven for computer scientists, with vast networks able to manipulate and analyze huge volumes of data at mind-boggling speeds,” the agency says on its website.

Beyond the damage assessment that’s routine following the loss of classified information, Hayden said, Snowden’s case should raise questions about operational issues, including whether a new generation of technology-savvy workers have a different view of secrecy than did their predecessors in the intelligence community.

“Will America be able to conduct espionage in the future inside a broader culture that demands more transparency and more public accountability from every aspect of national life?” Hayden asked.

The number of ads for jobs that require TS/SCI clearance is running at about double the level five years ago, according to Wanted Analytics, a company based in Quebec City that analyzes job listings. Most of those jobs are for computer specialists, such as software and network engineers.

“Recruiters are likely to find it difficult to hire candidates with TS/SCI clearance,” the company said in an April 2012 report.

The need to build technological intelligence operations has required the intelligence community to hire directly and through contractors a growing number of younger people such as Snowden who are sometimes called Internet natives, a shift that’s complicated the security clearance process, said two U.S. officials who asked not to be named discussing intelligence matters. The reason: They’ve done less, traveled less and established fewer patterns of behavior than older people, and their behavior is more subject to change.

Security clearances normally last five years before they must be renewed.

Snowden said he acted because he thought Americans should know what the government is doing in their name, and that its actions wrongly jeopardized privacy rights. His documents exposed the NSA’s program to obtain records of phone calls by Americans and to spy on Internet communications through a program called PRISM.

The security breach has been referred to the Justice Department, Shawn Turner, a spokesman for James Clapper, the director of national intelligence, said in an emailed statement.

“The intelligence community is currently reviewing the damage that has been done by these recent disclosures,” Turner said.

Snowden’s disclosures came as another self-described whistle-blower, Army Pvt. 1st Class Bradley Manning, 25, is on trial charged with providing a trove of classified State Department documents to WikiLeaks.

Manning, who’s admitted to providing hundreds of thousands of documents to the anti-secrecy website, plead guilty earlier this year to charges that could bring 20 years imprisonment. The military is conducting a court-martial on charges that include aiding the enemy, which carries a potential life sentence.

While it’s impossible to draw broad conclusions from two instances, the Snowden and Manning cases may reflect more widespread skepticism about government secrecy and greater support for individual privacy, as Hayden suggested.

These instances point to a “generational” difference between younger workers and older ones when it comes to keeping information secret and trusting the government, said James Lewis, technology program director at the Center for Strategic and International Studies in Washington.

“You’ve got kids that have grown up in this environment that is very hostile to government and very skeptical of government,” Lewis said in an interview. “If people don’t trust their government, then they’re going to be more prone to leak.”

The government should put more controls on who can access classified information, Lewis said, acknowledging that doing so is counter to the push since the 2001 terrorist attacks for agencies to make it easier to share data. A failure by the CIA and the Federal Bureau of Investigation to share information about two of the eventual hijackers has been cited as one reason authorities didn’t detect the plot.

“There’s a delicate balance here,” said Hayden, on the issue of the tension between sharing information within the government and erecting barriers to safeguard it.

“You don’t want to put that bar so high that you’re actually denying people information that they need to do their job,” he said.

Georgia Sen. Saxby Chambliss, the top Republican on the Senate intelligence committee, said he wasn’t particularly concerned that Snowden was a contractor.

“Whether someone is a contractor does not make them more likely to leak classified information,” he said in an emailed statement. “There are very good contractors in the intelligence community right now who serve their country honorably. Our focus should be on why this particular individual made the decision to betray his country, what steps can be taken to ensure this does not happen again, and how to repair the damage that has already been done.”

The focus on the activities of the Fort Meade, Md.- based NSA comes after a decade of rapid expansion by the organization and its contractors. Much of the NSA budget is hidden in other Defense Department accounts, and its own budget remains classified and is disclosed only to congressional oversight committees.

The NSA, which has about 42,000 government and contract workers, has been able to expand under the veil of “excessive secrecy” and without adequate congressional oversight, Jameel Jaffer, deputy legal director of the American Civil Liberties Union, said in an interview.

Along with McLean, Va.-based Booz Allen, other major intelligence community contractors include Boeing Co. of Chicago and, in suburban Washington, SAIC, Computer Sciences, CACI International, Lockheed Martin and Mantech International.

James Fisher, a spokesman for Booz Allen, declined to comment beyond a written statement the company posted June 9 on its website. The company said Snowden was an employee for less than three months assigned to a team in Hawaii.

“News reports that this individual has claimed to have leaked classified information are shocking, and if accurate, this action represents a grave violation of the code of conduct and core values of our firm,” according to the statement.

“I have talked to the heads of our intelligence agencies and, to a person, they tell me that they could not function effectively without the use of contractors,” Collins said. “They need their personnel, their technology and their expertise. Now, there’s a public policy question about whether that should be the case, but it is the reality today.”